As a culture, we've become upset by the tobacco companies advertising to children, but we sit idly by while the food companies do the very same thing. And we could make a claim that the toll taken on the public health by a poor diet rivals that taken by tobacco.

They may have salt, sugar, and fat on their side, but we, ultimately, have the power to make choices. After all, we decide what to buy. We decide how much to eat.

Each year, food companies use an amount of salt that is every bit as staggering as it sounds: 5 billion pounds.

Some of the largest companies are now using brain scans to study how we react neurologically to certain foods, especially to sugar. They've discovered that the brain lights up for sugar the same way it does for cocaine...

Every year, the average American eats as much as 33 pounds of cheese. That's up to 60,000 calories and 3,100 grams of saturated fat. So why do we eat so much cheese? Mainly it's because the government is in cahoots with the processed food industry. And instead of responding in earnest to the health crisis, they've spent the past 30 years getting people to eat more. This is the story of how we ended up doing just that.

As I spoke with scientists about the way fat behaves, I couldn't resist drawing an analogy to the realm of narcotics. If sugar is the methamphetamine of processed food ingredients, with its high-speed, blunt assault on our brains, then fat is the opiate, a smooth operator whose effects are less obvious but no less powerful.

What I found, over four years of research and reporting, was a conscious effort — taking place in labs and marketing meetings and grocery-store aisles — to get people hooked on foods that are convenient and inexpensive.